The method of the project is to examine the discharge of single neurons in the awake monkey's cerebellum during natural posture and movement. Our aim is to discover how cerebellar discharge differs from that of other parts of the motor system, and thus what unique properties the cerebellum contributes to the synthesis of posture and movement. Timing experiments in the previous grant periods suggest a sequence of neural events along anatomical pathways in which each station may contribute a property to the evolving motor command. Coding experiments systematically dissociated various aspects of movement of the wrist -pattern and force of muscular activity, angle of the wrist joint and mental anticipation of the direction of the next movement and showed that different stations in the anatomical and temporal sequential pathway are preferentially concerned with some variables as opposed to others. Experiments in the forthcoming period if granted will dissociate start and stop, rate and excursion of movement to see if these also are primary variables represented in cerebelllar output. Experiments will also dissociate anticipated movements from stimulus-guided movements to see if dentate and interpositus are differentially concerned with the one or the other. A second aim is to define precisely the output connections of the physiologically active areas in dentate and interposed nuclei by injecting radioactive amino acids. A third aim is to investigate synthesis of the cerebellar output by recording from the Purkinje cell. Experiments in the previous grant period provided some evidence in favor of cerebellar learning theories that granule cell inputs to Purkinje cells are modified over time by climbing fiber input. Experiments in the future will attempt to reproduce these results with more direct methods.